Comolded magnesite-chromite tuyere



April 9, 1963 H. A. MoRLocK 3,084,924

coMoLDEn MAGNESITE-CHRQMITE TUYERE |NvEN-roR HAAP/@Y 4. MUPLOCA/ April9,` 1963 H. A. MRLocK COMOLDED MAGNESITE'CHRQIIITE TUYERE 3 Sheets-Sheet2 Filed June 30. 1960 INVENTCR fm?" 4. Manac/r United States` Patent OThepresent invention relates to refractory tuyeres for metallurgicalfurnaces, especially for copper converters and Bessemer converters. i I

A purpose of the invention is to produce a tuyere brick which will havelonger service life and be more resistant v to erosion.

A further purpose is to facilitate the production of a tuyere brick bypressing and avoid the necessity of ramming.

A further purpose is to produce a tuyere -brick which willelectivelysea'l against -loss of gas notwithstanding that it is made ncooperating components.

A further purpose is to produce a tuyere brick that is more resistant-to spalling at the hot end.

Further purposes appear in the the claim. t

In the drawings I have ch-osen to illustrate a few only of the numerousembodiments in which the invention may appear, selecting the forms shownfrom the'standpoints of convenience in illustration, satisfactoryoperation and clear demonstration of -the principles involved.

FIGURE l is a diagrammatic transverse vertical section of a copperconverter embodying the invention.

FIGURE 2 is a fragmentary longitudinal section on the line 2--2 ofFIGURE 1.

FIGURE 3 is an enlarged fragmentary portion of FIG- URE 1 illustratingthe tuyeres, with the section' taken at a somewhat different point andnot actually through the tuyere passage.

specification and in version or 'Bessemerizatiom air is admittedbeneathth'e surface of a bath of moltenpmetallic sultides including'copper sulde, .to remove sulphur and iron by oxidation and slagging. v

'Ihere are other similar metallurgical or chemical processes to whichthe invention is applicable.`

These ltwo processes and others of similar nature are usually exothermicso that a great release of heat occurs which tends to keep the bathmolten without the necessity of adding additional fuel.

On the other hand, there are other reactions carriedv out in converterswhich are endothermic, in which case additional fuel must be introducedwithin the vessel to maintain the bath ina molten state. v

in both cases it is necessary that the interior of the vesseland thecharge be maintained at a high temperature,'.usually in excess of 2,000"F.

v head. V

The required pressure of the admitted air or other gases In both` of theprocesses mentioned, theair or other gases must be admitted below thesurface of the lliquid ba-th at considerable pressure to insure thatsu'icient volume of air will pass through the bath and promote thechemical reactions and overcome the hydrostatic pressure causes Igreatturbulence at the point where the gas enters the bath, and thisturbulence is further increased at that |point by the fact that the airor other gas is tremendously heated both by the molten bath and by thechemical reactions.

The turbulence therefore imparts energy to the molten bath so that dropsand splashes ofthe molten charge are expelled with great force from thesurface of the bath and propelled in an upward direction in the interiorof the FIGURE 4 is a fragmentary enlarged section at the cold end of thetuyere on the line 4,-4 of FIGURE 3.

FIGURE 5 is a face view of an individual'tuyere brick,

the view being in the position of the line 5--5 of FIG- URE 4.

FIGURE `6 is a fragmentary perspective of the tuyere brick of FIGURE 5.

FIGURE 6a ris a fragment of FIGURE 4 showing av variation.

FIGURE 7 is a view similar to FIGURE 3 showing a variation. v

FIGURE 8 is another view similar to FIGURE 3 showa further variation.

Describing in illustration but not in limitation and re# ferring to thedrawings:

The present invention has particular relation to a furnace wallconstruction involving tuyeres.

Certain metallurgical processes require that air or oxygen, or airenriched with oxygen, or 'other gases be introduced into a molten bathat pressures greater than atmospheric.V

metallurgical vessel. Some of this suspended, splashed material remainsmolten and returns to the bath either directly or by trickling down theinterior surface of the refractory lining. Some other higher meltingpoint portions of the splashed material freezes whi-le suspended in theinterior atmosphere of the vessel above the bath and these solidparticles arepropelled with relatively great force against the interiorof the vessel above the surface of the bath. Y

The pressure of gases and the weight of the molten liquid charge make itnecessary to contain such metallurgical furnaces or vessels within aheavy outer shell of steel plate. This outer steel shell is protected onits inner surface by a lining of refractory brick or tile components.'The refractory lining of the vessel must have suilcient thermalresistance to maintain a high temperature differential between its inneror hot end in contact with the molten bath and its outer or cold end incontact with the steel shell or adjacent the steel shell. The refractorylining must also be resistant to chemical attack by the molten bath andby the reaction products formed during the processing.

The refractory lining must also have greatl resistance to rupture fromthermal shock arising from fluctuations in temperature within themetallurgical vessel.

The vrefractory lining must also possess a high resistance to abrasionand erosion from turbulent molten material as e well as from particlesof suspended, frozen or solid material propelled against it.

Unless all of these influences which tend to destro;r

1the refractory lining are inhibited, early failure will occur. Becausethe purpose of the refractory lining is to protect the steel shellagainst weakness from high temperature or chemical attack, it isnecessary to replace the refractory lining when its original thicknesshas been reduced to the extent that it no longer protects the steel itwill lose its strength and -the moltenbath could be expelled through arupture in the shell, causing great danger to human life` as well aseconomic loss. The present invention is concerned with improving theintegrity of those highly stressed areas of the refractory lining whichform the tuyere.

In the prior art practice, in designing metallurgical vessels in whichblowing through the lining is to occur, a point is designated which willindicate the minimum ele-` vation of the molten bath. At some pointbelow this, a continuous opening or air passage through the refractorylining and through the steel shell is provided. Usually in practicethere are a series of such openings at the same elevation, eachcontinuing from the inner hot face of the refractory lining to the outerface of the refractory which is in contact with the inside of the steelshell and thence through holes in the steel shell to a point in theoutside where suitable piping connecting to a manifold or header duct isprovided, which in turn connects to a source of gas at superatmosphericpressure.

The pressurized air or gas is conducted through the opening in the shelland in the refractory lining into the interior of the vessel through theopenings or tuyeres which have been described.

In order vto better understand the construction, reference is made toFIGURES l and 2. These figures show a typical furnace or converterhaving an outer steel shell Z0, and an interior refractory lining 21intended to protect 'the metal shell 20, and having a charging anddischarging opening 22 near the top. The furnace normally rotates todischarge.

A molten charge 23 is placed in the furnace 4and this has atop surface24.

At an elevation below the top surface of the molten charge, tuyeres Zextend inwardly and suitably downwardly through the lining and themetallic shell to admit pressurizedair or gas beneath the surface of thebath. A header 26 along the outside of the furnace connects to theindividual tuyeres by pipes 27.

By reason of the factors already described, maximum turbulence andagitation of the liquid bath will occur adjacent the inside of thetuyeres.

The maximum intensity of chemical reactions will take place at the mouthof the tuyere, and hence the maximum temperature in the vessel willoccur at approximately this point.

differences in thermal conductivity through various parts By reason ofthe inertia of the liquid molten bath,

the zone in which the material will be splashed or ejected .from thesurface of the bath will be confined to that portion of the bathcontacting and close to the lining adjacent to the tuyere openings. Someportion of this ejected material will be propelled against the lining.Of this propelled portion of splashed material, a fraction will remainmolten and the balance will freeze or solidify while suspended in thevessel atmosphere. That fraction whichremains molten will trickle in adownward direction along the surface of the lining and tend to wash orerode a portion of particles of the lining.

Soliditied material which is propelled against the lining will thus tendto reduce the thickness of the lining by a mechanical action, which isanalogous to"sand blasting.

Although the area of the lining below the tuyeres cannot be observedduring blowing, it has been found experimentally that a high rate oferosion exists in this section of the lining caused by the abrasiveaction of the molten liquid bath moving in contact with the refractorylining. This movement of liquid material is caused by the currentcreated by the upwardly moving molten material.

lIt is found in practice that the zone of the lining at the tuyere andabove and below the tuyere requires most frequent replacement, and thisproves that itis subjected to more severe conditions than the remainderof the lining.

In FIGURE l I illustrate by a bracket 28 an area of the refractorylining above the tuyeres which is most effected by the expelledmaterial. I also illustrate by a bracket 30 an area of the liningbeneath the tuyeres which is most affected by the destructive forces.The molten and solid material expelled from the surface of the bath andpropelled ,against the lining is suggested by arrow 31, it beingunderstood that this arrow indicates a whole series of generallyadjoining travel paths of Agitated and turbulent material below thetuyere is shown by curved arrows 32 The refractory brick which conltainsthe tuyere opening is indicated at 33.-

the refractory lining above the worn section often loses its mechanicalsupport and falls from place. Hence any refractory lining above thetuyere which has further utility must be prematurely replaced, withcorresponding economic loss and loss of the productivity of the furnace.Accordingly it 'is very desirable tolengthen the service life of thezones 28 and 30 to reduce replacement cost of the refractory lining andlessen the down time of the furnace.

There are two additional factors which contribute to rapid wear of therefractory lining.

The first of these is the formation of zones of thermal instabilitywithin the body of the refractory brick. zones result from non-lineartemperature gradient between the hot faces and the cold faces of thebrick. This isv due to the variations in the density of the mass of therefractory components which form the lining, creating vof therefractory. -Where the temperature difference-between Aadjacent zones ishigh, great differences in thermal expansion will occur, with rupture ofthe refractory. This rupture liberates fragments of the refractory fromthe hot face and they Ifall from their places into the bath and diminishthe thickness of the lining. This vis a common phenomenon known asspalling.

4Another important factor which contributes to the destruction of therefractory lining -is mechanical impact.

During'the blowing period of the processing, metal, slags and othercompounds may become solid or frozen at the mouth of the tuyere andadhere tightly to the rethe lining material by displacing l fractoryaround the periphery of the tuyere opening. In some cases theseaccretions combine with the refractory at the hot face by fluxing Incommonpractice, an opening isprovided at the outer end of the tuyere toIinsert a steel bar and apply a heavy impact to the outer end of the barto force the bar through the .tuyere into the molten bath'and remove anyaccretions at the mouth of the tuyere and thus restore free ow o, airor-gases into the bath. This imposes a tension stress on the refractoryat the end of the tuyere. 'Iherefore any factor which inhibits orlessens the lowering of the tensile strength of the refractory isdesirable.

The usual practice followed in the present invention is to employ twoopposite counterpart tuyere bricks 33 side by side to form the tuyereopening. Each of these bricks has a refractory body 34 and has moldedtherein and extending longitudinally of the brick a semi-cylindricalportion 35 which forms half of the tuyere opening. FIG- URE 4 shows twoof the bricks 33 assembled to make the tuyere opening. It will beevident that while the tuyere opening is provided by` two bricks intheform shown, it may be formed by bricks having different lines ofseparation, whose relative position is superimposed y' particles.

These The preferred form of the tuyere brick as shown is of wedge or keyshape, provided with a relatively smaller hot shaped bricks or tiles 42of desired character form the refractory above and below the tuyere.

It is important to develop in the tuyere and in the areas above andbelow the tuyere characteristics which will improve the resistance toabrasion and erosion and the tensile and abrasive strength lof therefractory close vto the molten charge.

It is also important to increase the resistance to rupture, so -that thebrick will not separate into fragments and thus decrease the thicknessof the lining and cause overheating and weakening of the outer shell.

In my United States Patent 2,125,192, I describe bricks which have thinsteel plates in the joints, so as to form joints of iron oxide. 'Thistends to retain fragmentstor spalls by the effect of the iron oxidejoint.

This iron oxide joint actually has higher thermal con'- ductivity thanthe refractory so that a greater amount of heat is transmitted by thisjoint toward the outside. This tends to distribute the heat moreuniformly through the thickness of the refractory so that Vthetemperature drop will be approximately linear between the hot and thecold face.

Furthermore, the heat which reaches` the outer wall or shell can beradiated without overheating the shell. This tends to reduce the effectof localized zones of abnormally high temperature.

The ow of heat through such iron oxide joints to the outside tends alsoto maintain the hot faoe of the refractory at a lower temperature, sothat the refractory can remain reliably below the temperature ofincipient fusion, and better tensile and abrasive properties areobtained, as well as better resistance to abrasion and erosion.

In accordance with the present invention, very much superior tuyeres areproduced, which have greater tendency to retain spalls or fragments, andalso greater heat ilow from the hot face to the cold face. Superiorresistance to erosion and mechanical shock is also obtained.

In accordance with the invention, each tuyere brick 33 is composed ofmagnesia or a mixture of chromite and magnesia containing at least 10percent of magnesia by weight.

I provide on the face 40 which is to adjon the cooperating tuyere brickan external oxidizable metallic plate 43 which s desirably of rhomboidform, and covers a portion of the brick at one side of the tuyereopening. I also provide an external oxidizable metallic plate 44suitably of rhomboid form which substantially occupies the face 40 ofthe brick on the opposite side of the tuyere passage 35.

Secured to the external oxidizable metallic plate 43 is a U shapedinternal plate 45 having a base of the U 46 united to the plate 43 as byspot welding and having arms of the U 47 extending into the refractoryin comolded relation. The internal plate 4S is cut off diagonally so asnot to interfere with the tuyere opening. Extending inwardly from theplate 44 are internal oxidizable metallic plates 48 and 50 each havingbases of the U 51 or 52 extending along the inside of the internal plate44 and united thereto as by spot welding, and having arms of the U 53 or54 which extend into the refractory in comolded relation. The plates 48and 50 are cut olf diagonally to avoid the tuyere opening.

All of the oxidizable metallic internal and external plates are suitablymade of steel, including plain carbon or low alloy steel. Stain-lesssteel may be used as long as it is oxidizable at the temperature of use.The external and internal plates will have a thickness in the rangebetween %4 and 1A inch and preferably about ,z to Vs inch.

The external and internal plates are formed by suitably placing them inthe bottom of a mold with the plates 43 and 44 resting on the bottom ofthe mold and the internal plates protruding upwardly amid the mass ofrefractory, and then applying pressure at the face 41 against the 'face40 so that the external and internal plates are united. to therefractory by comolding.

It will be evident that the internal plates run generally transverse tothe top end of the brick and generally ra- .dially of the tuyere Ibrick.It will be evident that if desired an oxidizable metallic plate can alsobe applied on the face 41 of the tuyere brick, suitably by comolding.'

In some cases it is desirable to form a comolded oxidizable metallicplate on the inside of the tuyere opening and I show in FIGURE 6a afragment of the tuyere brick which has such an oxidizable metallic plateat 55 extending longitudinally of the tuyere opening, the plate 55suitably being integral with the plates 43 and 44.

It will be evident that it is not specifically critical in the presentinven-tion as to whether the internal plates extend wholly from plateson the face 40 or wholly from plates on the face 4l, or in part fromplates on the face 40 and in part from plates on the face 41. vj -Itwill also be evident that the comolded internal plates which areItransverse to the hotface can extend in from other faces of the brickas desired. Y

It .will be understood that the steel plates which are on the outsideand which meet in FIGURE 4 at the face 40 will oxidize and formv zonesof iron oxide extending toward the cold end. This will also be true ofthe internal plates and the internal plates will react with the magnesiato form magnesioferrite. Thus a large number of cells will be formed andthe iron oxide ribs and the magnesioferrite nbs will tend to preventspalling and damage lfrom abrasion and Will also conduct heat outvwardly. These conducting paths yield some of their heat to therefractory mass and make the refractory mass more uniform in temperaturedrop, and also more readily transfer heat to the outer steel shell forradiation. This tends to reduce abnormally high hot face temperature atthe tuyere.

The key or wedge bricks 42 will suitably also be provided with comoldedexternal plates 56 and radially ex tending internal plates 57 securedthereto as shown in FIGURE 7. In this figure heat insulating spacerbricks 58 are provided between the wedge or key bricks 42 and the shell,as well as a loose refractory layer 60 which extends between the shelland the tuyere brick as well as the wedge or key bricks.

In FIGURE 8 I illustrate a somewhat diiferent construction, in which thewedge or key bricks 42 and the tuyere bricks 33 are Ihacked up by heatinsulating bricks 61 which in some cases at 62 have openings to connectwith the tuyeres. In this case the metallic shell 20 is reenforced at 20adjoining the tuyeres.

In view of my invention and disclosure variations and modifications tomeet individual whim or vparticular need will doubtless become evidentto others skilled inthe art, to obtain all or part of the benefits of myinvention without copying the structure shown, and I therefore, claimall such insofar as they rfall within the reasonable spirit and'scope ofmy claim.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

In a copper converter for molten metal to be blown with air introduced'below the line of the molten metal, a housing, a refractory liningextending rthroughout the interior of the housing and tuyeres formed bycooperating tuyere brick of basic refractory of the c lass consisting ofmagnesia and mixtures of chromite and magnesia containing at least 10%of magnesia, said tuyere brick extending with their inner ends in theinterior of the con- 'verter below the metal line and passages of saidtuyeres communicating with the molten metal below the metal line throughthe inner ends of said brick in the converter, each said tuyere brickfor-ming only a portion of a cor- 7 responding one of said tuyerepassages which extends from the interior of the converter outwardlygenerally longitudinally of the brick forming said portion, there beingan oxidizable ferrous metallic external plate cover ing the matingcooperating faces of the tuyere 'bricksv and there being oxidizableferrous metallic internal plates extending in the interior of therefractory of said tuyere bricks adjacent to the tuyere passages andsaid inner ends of the brick and secured to said external plates, andsaid external and internal plates being in comolded relation with thelrefractory and extending generally longitudinally of the tuyere bricks.

. UNITED STATES PATENTS Morlock July 26, Heuer lan. 28, Zippler Dec. 30,Cope Ian. l, Heuer et al. May 7, Kelsey Dec. 3l,

FOREIGN PATENTS Germany lan. 28, Canada Apr. 2l,

